This invention relates to cooling systems for vehicles, and more particularly, to a vehicular cooling system that reduces fuel consumption and which provides more traction power.
Vehicular cooling systems are becoming increasingly complex. While the cooling systems on early internal combustion engine powered vehicles were as simple as the provision of fins on the exterior of the cylinders of the engine to provide air cooling of the engine, they have evolved significantly. In today""s world, the use of liquid cooled engines requires the vehicle to have a radiator to cool the liquid engine coolant. Moreover, where the engine is turbocharged, it is desirable to cool the compressed air exiting the turbocharger to increase its density and increase engine efficiency. This necessitates a so-called intercooler or charge air cooler.
Frequently, too, engine and/or transmission fluids such as lubricating or hydraulic oil, or both, require cooling to prevent damage to the components with which they contact.
These components may be referred to as power train heat exchangers inasmuch as the heat rejection required of them is almost entirely dependent upon engine loading. The higher the engine load, the more heat that must be rejected.
At the same time, modern vehicles typically are equipped with air conditioning systems operating on the vapor compression system. As a consequence, it is necessary that the air conditioning system include a condenser or gas cooler (the terms are used interchangeably herein) for cooling refrigerant by rejecting heat to the ambient air. While refrigerant heat rejection is related to the ambient temperature and to the control setting of the air conditioning system, typically located within a passenger compartment, power train heat rejection is related to the fuel combustion rate of the engine. Higher fuel consumption requires higher engine coolant, charge air, and transmission or engine oil heat rejection. And ambient temperature does not significantly increase the heat rejection required of the power train. Rather, it simply decreases the temperature difference between the power train fluids and the ambient.
Thus, because power train and air conditioning system heat rejection rates are basically independent of one another, the application of conventional wisdom has resulted in only a very minimum integration of the respective systems, where there has been any integration of them at all. As a result, the total vehicle cooling system, which is the sum of both power train cooling systems and air conditioning systems has resulted in overly large heat exchangers to assure maximum heat rejection when required as well as a relatively high fan horsepower requirement to assure that the maximum rate of cooling air can be flowed through all of the heat exchangers involved. This not only adds to the expense of the system, it adds to the cost of operating it because of excessive fan horsepower requirements.
The present invention is directed to overcoming these difficulties.
It is the principal objection of the invention to provide a new and improved vehicular cooling system. More specifically, it is an object of the invention to provide such a cooling system wherein fan horsepower requirements are minimized and which allows the use of smaller heat exchangers than would be required for a conventional cooling system for a similar vehicle.
According to the preferred embodiment of the invention, there is provided a vehicular cooling system which includes an inlet for the receipt of ambient air. First and second heat exchangers are located in proximity to the inlet to receive ambient air therefrom and are respectively adapted to receive first and second heat exchange fluids to be cooled by the ambient air. The first and second heat exchangers are in side by side, substantially non-superimposed relation to define first and second air flow paths, respectively, extending in fluid flow parallel through a respective one of the heat exchangers from the inlet to one or more points of discharge. One or more fans are provided for flowing air from the inlet through the first and second flow paths. A shutter is located in one of the flow paths and is movable between a first position relatively restricting air flow through the one flow path and a second position allowing relatively unrestricted air flow through the one flow path and additional positions intermediate the first and second positions. An actuator is provided for moving the shutter between the positions.
In a highly preferred embodiment, a control is provided for the actuator.
In a preferred embodiment of the invention, the second heat exchanger is a gas cooler for an air conditioning system and the shutter is in the second flow path.
Preferably the shutter comprises first and second, relatively movable grates.
In one embodiment, one of the grates is fixed with respect to the second heat exchanger and the other of the grates is movably mounted with respect to the second heat exchanger. The actuator is connected to the movably mounted grate.
In one embodiment, the control includes a fan drive controller for the fan(s) and is operative to a) control the speed of the fan(s) and b) provide a position control signal for the actuator.
The invention contemplates that the first heat exchanger is a radiator for cooling engine coolant and the second heat exchanger is a gas cooler for an air conditioning system. The control includes a fan controller providing a xe2x80x9cfan onxe2x80x9d set point, a transducer for monitoring the temperature of the first fluid, and a comparator for comparing the monitored temperature with the set point and causing the actuator to a) move the shutter toward the first position when the monitored temperature exceeds the set point and b) move the shutter toward the second position when the monitored temperature does not exceed the set point.
The invention contemplates that the first and second heat exchangers be arranged as adjacent sides of a polygonal solid.
In a highly preferred embodiment, there are two of the first heat exchangers and the second heat exchanger has one side adjacent one of the first heat exchangers and an opposite side adjacent the other of the first heat exchangers. A third heat exchanger is located oppositely of the second heat exchanger and has a first side adjacent one of the first heat exchangers and an opposite side adjacent the other of the first heat exchangers. The fan(s) is surrounded by the heat exchangers.
According to the embodiment of the preceding paragraph, the heat exchangers are arranged as respective sides of a polygonal solid having a trapezoidal cross section.
In one embodiment of the invention, the shutter includes a fixed element and a movable element mounted for movement relative to the fixed element. A first link is connected to the fixed element by a first pivot and is connected to the actuator. A second link is connected to the movable element by a second pivot and to the first link by a third pivot spaced from the first pivot.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.